package com.andova.toolkit.util;

import android.content.Context;
import android.content.SharedPreferences;
import android.provider.Settings.Secure;
import android.telephony.TelephonyManager;

import java.util.UUID;

import static kotlin.text.Charsets.UTF_8;

public class DeviceIdFactory {
    protected static final String PREFS_FILE = "device_id.xml";
    protected static final String PREFS_DEVICE_ID = "device_id";
    protected static volatile UUID uuid;

    public DeviceIdFactory(Context context) {
        if (uuid != null) return;
        synchronized (DeviceIdFactory.class) {
            if (uuid == null) {
                final SharedPreferences prefs = context.getSharedPreferences(PREFS_FILE, Context.MODE_PRIVATE);
                final String id = prefs.getString(PREFS_DEVICE_ID, null);
                if (id != null) {
                    // Use the ids previously computed and stored in the
                    // prefs file
                    uuid = UUID.fromString(id);
                } else {
                    final String androidId = Secure.getString(context.getContentResolver(), Secure.ANDROID_ID);
                    // Use the Android ID unless it's broken, in which case
                    // fallback on deviceId,
                    // unless it's not available, then fallback on a random
                    // number which we store to a prefs file
                    if (!"9774d56d682e549c".equals(androidId)) {
                        uuid = UUID.nameUUIDFromBytes(androidId.getBytes(UTF_8));
                    } else {
                        final String deviceId = ((TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE)).getDeviceId();
                        uuid = deviceId != null ? UUID.nameUUIDFromBytes(deviceId.getBytes(UTF_8)) : UUID.randomUUID();
                    }
                    // Write the value out to the prefs file
                    prefs.edit().putString(PREFS_DEVICE_ID, uuid.toString()).apply();
                }
            }
        }
    }

    /**
     * Returns a unique UUID for the current android device. As with all UUIDs,
     * this unique ID is "very highly likely" to be unique across all Android
     * devices. Much more so than ANDROID_ID is.
     * <p>
     * The UUID is generated by using ANDROID_ID as the base key if appropriate,
     * falling back on TelephonyManager.getDeviceID() if ANDROID_ID is known to
     * be incorrect, and finally falling back on a random UUID that's persisted
     * to SharedPreferences if getDeviceID() does not return a usable value.
     * <p>
     * In some rare circumstances, this ID may change. In particular, if the
     * device is factory reset a new device ID may be generated. In addition, if
     * a user upgrades their phone from certain buggy implementations of Android
     * 2.2 to a newer, non-buggy version of Android, the device ID may change.
     * Or, if a user uninstalls your app on a device that has neither a proper
     * Android ID nor a Device ID, this ID may change on reinstallation.
     * <p>
     * Note that if the code falls back on using TelephonyManager.getDeviceId(),
     * the resulting ID will NOT change after a factory reset. Something to be
     * aware of.
     * <p>
     * Works around a bug in Android 2.2 for many devices when using ANDROID_ID
     * directly.
     *
     * @return a UUID that may be used to uniquely identify your device for most
     * purposes.
     * @see http://code.google.com/p/android/issues/detail?id=10603
     */
    public UUID getDeviceUuid() {
        return uuid;
    }

    public long getDeviceId() {
        int userId = uuid.toString().hashCode();
        userId = userId < 0 ? -userId : userId; // String.hashCode()可能会是负数，如果为负数需要转换为正数
        return Long.parseLong(String.valueOf(userId));
    }
}